buzz / rattles between certain RPMs during quick acceleration
 

Hi all :)

I purchased a used gts86 with automatic transmission from a dealer a week ago and I notice this light rattle between 2500 - 3000 RPM consistently during quick acceleration.It sounds like the rattle comes from the driver side. Also, there is NO rattle if I put the P mode and hand brake on and just revv the engine.

The rattle is pretty much identical to the sound produced from this video:

[ame="https://www.youtube.com/watch?v=6uTUaCBhGiQ&index=153&list=WL"]FRS engine rattle. at @00:03 and 00:24s - YouTube[/ame]

I have booked an appointment with Toyota this Thursday but I would much prefer to get some opinions from your guys about the nature of the rattle.

Thanks in advance!

P.S. Its a fantastic car but the rattle takes away the joy from riding it, since it can be consistently produced.

I'm taking my car in for a transmission inspection this saturday based on almost the same noise. I'm expecting it to be a "normal" thing but want it checked out before my BRZ goes OOW.

I suspect its my flywheel that rattles. its odd though because its most noticeable at lower rpms, clutch not pressed. When the fans kick in, its more audible too.

Thanks for your input and please excuse me for the lacking of knowledge in cars, but does the automatic transmission come with a flywheel as well? Either way,I don't think it's a normal behaviour right? I only hope my dealership will be able to hear the rattle and fix it.

Sounds like someone forgot to bolt down the bottom engine covers.

Thanks for the input :) Just wondering though, wouldn't the rattle be heard even the car is not in gears while revving the engine, if the bottom cover of engine goes loose?

Well if that's the case it could be the motor/tranny mounts that are lose

It could be that when the engine torques over a bit, that a heat shield is hitting on something ...... I suggest you get it up on a rack and poke around, looking for things that are close together and could rattle.


humfrz

I will make sure to hint the dealership tomorrow if he fails to hear the rattle. thanks.

Well, let's hope they find and fix it.

Please keep us posted.


humfrz

UPDATE 1: the inspection took place few hours ago. The technician went on a test drive with me after I verbally depicted the issue to him. He heard the rattle during the test drive and afterwards he said a further diagnose of the vehicle was needed, including driving another 86 with a similar manufactured date and communicating with Toyota to ensure if the rattle was the characteristic of the car or not. However, he did mention a thing or two about the rattles perhaps had something to do with the exhaust, engine and flywheel and didn't think it was merely interior rattles. On a side note, he also mentioned my car had a rougher handling than previous 86 he had driven, as he felt vibration from the steering wheel or something was not levelled <= can't remember exactly what he said for this part.

Currently the car is with Toyota and I will update you guys once I have my updates from them. Thanks !

P.S. this is my first car and I bought it used from a dealer. Based on the previous owner of the car and a thorough service record, I only thought the car would only have some cosmetic issues, such as scratches or dents, and it would not have any mechanical problems. I guess I thought wrong. Also, I don't think the rattles are the nature characteristic of the car --- rattles during certain rpm under load but they are non existed when the car is not in gear? nah..

The rattling is definitely not normal behavior, and like others have said is probably from a loose panel or something else vibrating against something else. The reason you may not hear it when not in a driving gear is because in park or neutral there is no load on the engine. Things behave a little differently when the engine is loaded, whether it be that they move/vibrate a little differently/more, or sound different.

Ever notice how when you go from Park or Neutral into Drive that the rpms drop a little bit as the car goes into gear? That's putting a load on the engine, giving it something to do...in this case move the car forward. Without that load all it has to do is spin, which is pretty effortless. In gear, now it's got more machinery to move, and you'd be surprised how much things you'd expect to be rigid do move under the hood and under the car. Vibrations and frequencies are strange things.

Anyway, point being, something is probably loose, maybe missing a few bolts, like a heat shield or one of the underbody panels, or an exhaust bushing may have fallen off or not even be there, letting the pipes move around a lot more than they should. That's my guess, and hopefully that tech will start with those simple things before trying to deep dive into some exotic possibility.

Also, yes, your automatic car does have a flywheel, it's just usually a slightly different design than what is in a manual car, but still performs the same function. I do not suspect that is your issue, though.

Keep us posted.

Thanks for your insights :) I only hope Toyota won't deem it as a normal behaviour due to business practices and I also hope the tech can pinpoint the exact issue and fix it. I was gonna get an Audi A4 but then the appeal of the 86 won my heart....and the car is only 1 week old to me..despite its a used model.

In general sports cars are noisy, an Audi A4 is more a luxury vehicle.
I wouldn't be too concerned but let us know what Toyota say ;)

UPDATE 2: can't believe Toyota tech got back to me just then and I was told on the phone that my tech guy tried out another 86 and it made an exact same noise and it came from the exhaust. so they wanted me to ride with them tomorrow on another 86 and showed it to me.

Me: I was speechless when I heard it over the phone. so the exhaust is supposed to rattle and the noise can't be quiet down by stabilising the exhaust? also how come I don't see any posts from 86 forum where this kind of symptom was asked.